1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Masquerade. Simple mapping which alters range to a local IP address
3 (depending on route). */
4
5 /* (C) 1999-2001 Paul `Rusty' Russell
6 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
7 */
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9 #include <linux/module.h>
10 #include <linux/netfilter/x_tables.h>
11 #include <net/netfilter/nf_nat.h>
12 #include <net/netfilter/nf_nat_masquerade.h>
13
14 MODULE_LICENSE("GPL");
15 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
16 MODULE_DESCRIPTION("Xtables: automatic-address SNAT");
17
18 /* FIXME: Multiple targets. --RR */
masquerade_tg_check(const struct xt_tgchk_param * par)19 static int masquerade_tg_check(const struct xt_tgchk_param *par)
20 {
21 const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
22
23 if (mr->range[0].flags & NF_NAT_RANGE_MAP_IPS) {
24 pr_debug("bad MAP_IPS.\n");
25 return -EINVAL;
26 }
27 if (mr->rangesize != 1) {
28 pr_debug("bad rangesize %u\n", mr->rangesize);
29 return -EINVAL;
30 }
31 return nf_ct_netns_get(par->net, par->family);
32 }
33
34 static unsigned int
masquerade_tg(struct sk_buff * skb,const struct xt_action_param * par)35 masquerade_tg(struct sk_buff *skb, const struct xt_action_param *par)
36 {
37 struct nf_nat_range2 range;
38 const struct nf_nat_ipv4_multi_range_compat *mr;
39
40 mr = par->targinfo;
41 range.flags = mr->range[0].flags;
42 range.min_proto = mr->range[0].min;
43 range.max_proto = mr->range[0].max;
44
45 return nf_nat_masquerade_ipv4(skb, xt_hooknum(par), &range,
46 xt_out(par));
47 }
48
masquerade_tg_destroy(const struct xt_tgdtor_param * par)49 static void masquerade_tg_destroy(const struct xt_tgdtor_param *par)
50 {
51 nf_ct_netns_put(par->net, par->family);
52 }
53
54 #if IS_ENABLED(CONFIG_IPV6)
55 static unsigned int
masquerade_tg6(struct sk_buff * skb,const struct xt_action_param * par)56 masquerade_tg6(struct sk_buff *skb, const struct xt_action_param *par)
57 {
58 return nf_nat_masquerade_ipv6(skb, par->targinfo, xt_out(par));
59 }
60
masquerade_tg6_checkentry(const struct xt_tgchk_param * par)61 static int masquerade_tg6_checkentry(const struct xt_tgchk_param *par)
62 {
63 const struct nf_nat_range2 *range = par->targinfo;
64
65 if (range->flags & NF_NAT_RANGE_MAP_IPS)
66 return -EINVAL;
67
68 return nf_ct_netns_get(par->net, par->family);
69 }
70 #endif
71
72 static struct xt_target masquerade_tg_reg[] __read_mostly = {
73 {
74 #if IS_ENABLED(CONFIG_IPV6)
75 .name = "MASQUERADE",
76 .family = NFPROTO_IPV6,
77 .target = masquerade_tg6,
78 .targetsize = sizeof(struct nf_nat_range),
79 .table = "nat",
80 .hooks = 1 << NF_INET_POST_ROUTING,
81 .checkentry = masquerade_tg6_checkentry,
82 .destroy = masquerade_tg_destroy,
83 .me = THIS_MODULE,
84 }, {
85 #endif
86 .name = "MASQUERADE",
87 .family = NFPROTO_IPV4,
88 .target = masquerade_tg,
89 .targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
90 .table = "nat",
91 .hooks = 1 << NF_INET_POST_ROUTING,
92 .checkentry = masquerade_tg_check,
93 .destroy = masquerade_tg_destroy,
94 .me = THIS_MODULE,
95 }
96 };
97
masquerade_tg_init(void)98 static int __init masquerade_tg_init(void)
99 {
100 int ret;
101
102 ret = xt_register_targets(masquerade_tg_reg,
103 ARRAY_SIZE(masquerade_tg_reg));
104 if (ret)
105 return ret;
106
107 ret = nf_nat_masquerade_inet_register_notifiers();
108 if (ret) {
109 xt_unregister_targets(masquerade_tg_reg,
110 ARRAY_SIZE(masquerade_tg_reg));
111 return ret;
112 }
113
114 return ret;
115 }
116
masquerade_tg_exit(void)117 static void __exit masquerade_tg_exit(void)
118 {
119 xt_unregister_targets(masquerade_tg_reg, ARRAY_SIZE(masquerade_tg_reg));
120 nf_nat_masquerade_inet_unregister_notifiers();
121 }
122
123 module_init(masquerade_tg_init);
124 module_exit(masquerade_tg_exit);
125 #if IS_ENABLED(CONFIG_IPV6)
126 MODULE_ALIAS("ip6t_MASQUERADE");
127 #endif
128 MODULE_ALIAS("ipt_MASQUERADE");
129